ABSTRACT
The present study describes the effect of a hypertonic increase in sodium chloride concentration on electrophysiological parameters. Membrane depolarization was recorded from rabbit Purkinje fibers superfused with warm, aerated Tyrode solution. An amount of 5% NaCl above that in normal Tyrode solution (HyNaCl, 344 mOsm) was added to the bathing medium for 30 min, significantly increasing the maximal rate of depolarization (Vmax + 15% vs - 7% for control), with minor effects on other parameters. When bupivacaine was superfused over the preparation for 30 min either in normal Tyrode or in HyNaCl, Vmax was significantly deveased (33% and 15%, respectively). HyNaCl protected the cardiac tissues from the depressive effect of 05micron/ml bupivacaine. We suggest that the infusion of hypertonic saline in intact animals may prove effective in preventing or reversing the cardiodepressant effect of bupivacaine